US6480775B2 - Method for controlling continuously variable transmission - Google Patents

Method for controlling continuously variable transmission Download PDF

Info

Publication number
US6480775B2
US6480775B2 US09/898,619 US89861901A US6480775B2 US 6480775 B2 US6480775 B2 US 6480775B2 US 89861901 A US89861901 A US 89861901A US 6480775 B2 US6480775 B2 US 6480775B2
Authority
US
United States
Prior art keywords
speed ratio
cvt
control method
driving pattern
vehicle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US09/898,619
Other languages
English (en)
Other versions
US20020082758A1 (en
Inventor
Yoon-Ho Cho
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hyundai Motor Co
Original Assignee
Hyundai Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hyundai Motor Co filed Critical Hyundai Motor Co
Assigned to HYUNDAI MOTOR COMPANY reassignment HYUNDAI MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHO, YOON-HO
Publication of US20020082758A1 publication Critical patent/US20020082758A1/en
Application granted granted Critical
Publication of US6480775B2 publication Critical patent/US6480775B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/02—Selector apparatus
    • F16H59/04—Ratio selector apparatus
    • F16H59/06—Ratio selector apparatus the ratio being infinitely variable
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F16H61/662—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members
    • F16H61/66254—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling of shifting being influenced by a signal derived from the engine and the main coupling

Definitions

  • the present invention relates to a method for controlling a continuously variable transmission (CVT), and more particularly to a method capable of automatically controlling a speed ratio between economic and power modes without manual mode selection.
  • CVT continuously variable transmission
  • An automotive transmission is a device for transmitting engine torque to a drive shaft of a vehicle in variable speed ratios, and transmissions are usually classified into manual, automatic, and continuously variable transmissions (CVT).
  • CVT continuously variable transmissions
  • the CVT can vary the speed ratio continuously.
  • engine revolution speed can be optimally selected such that an engine operates at a preferred revolution-per-minute (rpm) relative to one of intended conditions such as maximum mileage, maximum output, minimum noise, minimum toxic gas emission, etc.
  • the speed ratio of the CVT is determined by engine torque-rpm maps that are preset according to intended conditions such as maximum mileage (economy mode) and maximum power (power mode).
  • FIG. 4 is a graph showing engine performance curves.
  • Curve 1 indicates a plurality of iso-Brake Specific Fuel Consumption (iso-BSFC) curves and P 0 indicates a point where the fuel consumption is the lowest.
  • Curve 3 indicates a maximum mileage curve, which passes through the lowest fuel consumption point P 0 .
  • Curve 4 indicates a maximum power control curve.
  • the speed ratio can be randomly shifted in an available range such that the engine rpm and the engine torque can be randomly set regardless of the vehicle speed.
  • the CVT is controlled in such a way that the engine performs with a specific torque and rpm along the maximum mileage curve C 3 to provide maximum mileage of a vehicle, and it performs with another specific torque and rpm along the maximum power control curve C 4 for maximum power driving.
  • the speed ratio of the CVT is determined on the basis of a throttle valve opening and vehicle speed values specified in the map corresponding to the control mode that are determined relative to the intended driving condition, such as maximum mileage or maximum power.
  • a conventional CVT control method requires mode selection input from the driver, and the mode selection process can cause the speed ratio to be abruptly changed, resulting in shift shock, vibration, and engine shaking.
  • the present invention has been made in an effort to solve the above problems of the prior art.
  • a CVT control method of the present invention comprises the steps of calculating a target speed ratio of a CVT between maximum and minimum values of a plurality of speed ratios preset corresponding to a plurality of engine operation modes and controlling the CVT according to the target speed ratio.
  • the step of calculating the target speed ratio includes the steps of calculating a driving pattern index on the basis of throttle opening change rate, throttle operation frequency, and vehicle acceleration, and calculating the target speed ratio on the basis of the driving pattern index.
  • a, b, and c are respectively a learned throttle opening change rate, learned throttle operation frequency, and learned vehicle acceleration;
  • a 0 , B 0 , and C 0 are respectively a preset throttle opening change rate, preset throttle operation frequency, and preset vehicle acceleration.
  • the CVT control method according to the present invention can further includes the steps of determining if a learning condition is satisfied, and learning the driving pattern index when the learning condition is satisfied.
  • the learning condition can be defined as 'The present change rate of throttle opening is different from an average change rate of throttle opening up to this point by more than a predetermined difference, or the present throttle operation frequency is different from an average throttle operation frequency up to this point by more than a predetermined frequency, or the present acceleration is different from an average acceleration up to this point by more than a predetermined acceleration.
  • the CVT control method of the present invention can further include the step of determining whether the vehicle is running at a constant speed, wherein the step of calculating a driving pattern index is performed if the vehicle is not running at a constant speed.
  • the target speed ratio is determined to be one of default engine operation modes, which is preferably an economy mode.
  • FIG. 1 is a block diagram illustrating a CVT control system according to the present invention
  • FIG. 2 is a flow chart illustrating a CVT control method according to a preferred embodiment of the present invention
  • FIG. 3 is a flow chart illustrating sub-steps of a fuzzy calculation step of FIG. 2;
  • FIG. 4 is a graph illustrating exemplary engine performance curves.
  • FIG. 1 is a block diagram illustrating a CVT control system according to the present invention.
  • the CVT control system comprises a throttle sensor 110 for sensing throttle opening, a speed sensor for sensing vehicle speed, a CVT 130 for transmitting torque from an engine (not shown) to an output shaft, and a transmission control unit (TCU) 140 electrically connected to the throttle sensor 110 , speed sensor 120 , and CVT 130 such that the TCU 140 controls the CVT 130 on the basis of parameters from the throttle and speed sensors 110 and 120 .
  • TCU transmission control unit
  • the TCU 140 determines whether the vehicle is running at a constant speed or not on the basis of the parameters from the speed sensor 120 at step S 210 .
  • the TCU 140 calculates a target speed ratio for the CVT according to a default control mode at step S 230 and then controls the CVT according to the calculated target speed ratio at step S 260 .
  • a mode conversion is not required such that the CVT control is performed in the preset default control mode. It is preferred to set an economy mode as the default.
  • the TCU 140 starts a fuzzy calculation for obtaining a target speed ratio at step S 220 .
  • the fuzzy calculation is a calculation to determine the speed ratio between a preset power mode speed ratio and a preset economy mode speed ratio using a learning process.
  • step S 220 The fuzzy calculation method for obtaining the target speed ratio in step S 220 will be described in more detail hereinafter, with reference to FIG. 3 .
  • the TCU 140 firstly receives the throttle opening and vehicle speed parameters detected by the throttle opening sensor 110 and vehicle speed sensor 120 at step S 310 .
  • the vehicle speed obtained at step S 210 can also be used instead of sensing again at step S 310 .
  • the TCU 140 calculates the throttle opening change rate, throttle operation frequency, and vehicle acceleration at step S 320 .
  • the throttle opening change rate means how fast an acceleration pedal is depressed , that is, how fast the throttle opening is changed.
  • the throttle operation frequency means how frequently the acceleration pedal is operated in a predetermined period.
  • a driving pattern index (X) is calculated at step S 330 , using equation 1.
  • X ( ⁇ ⁇ a A0 + ⁇ ⁇ b B0 + ⁇ ⁇ c C0 ) / 3 Equation ⁇ ⁇ 1
  • parameters a, b, and c respectively indicate a learned throttle opening change rate, a learned throttle operation frequency, and a learned vehicle acceleration.
  • the learned throttle opening change rate “a” is obtained by adding a throttle opening change rate index (F a ) to the previously calculated throttle opening rate.
  • the result value is mapped to 0 if it is less than 0, and mapped to A 0 if it is greater than A 0 . It is preferred that the throttle opening change rate index (F a ), which is learned as driving history is accumulated, is initially set to 0.
  • the learned throttle operation frequency “b” is calculated on the basis of throttle operation index (F b ) and B 0
  • a learned vehicle acceleration “c” is calculated on the basis of vehicle acceleration index (F c ) and C 0 , in the same way as the learned throttle opening rate “a.”
  • the parameters A 0 , B 0 , and C 0 respectively indicate a preset throttle opening change rate, a preset throttle operation frequency, and a preset vehicle acceleration.
  • the preset throttle opening change rate, preset throttle operation frequency, and preset vehicle acceleration A 0 , B 0 , and C 0 are respectively set to a maximum throttle opening change ratio, a maximum throttle operation frequency, and a maximum vehicle acceleration that can be generated by the driver's manipulation.
  • the pattern indices according to the throttle opening change rate, throttle operation frequency, and vehicle acceleration can be expressed as a/A 0 , b/B 0 , and c/C 0 , each value of which is greater than 0 and less than 1.
  • the driving pattern index (X) calculated through Equation 1 has a value greater than 0 and less than 1.
  • the TCU 140 calculates a target speed ratio (Tm) at step S 340 .
  • the target speed ratio is calculated between the economy mode speed ratio (Te) and the power mode speed ratio (Tp) on the basis of the driving pattern index (X) using Equation 2.
  • Tm ( Tp ⁇ Te ) X+Te Equation 2
  • the driving pattern index (X) has a value between 0 and 1 through Equation 2 such that the target speed ratio (Tm) has a value between the economy mode speed ratio (Te) and the power mode speed ratio (Tp).
  • the TCU 140 determines whether a predetermined learning condition is satisfied at step S 240 .
  • the predetermined learning condition can be deliberately set as in the following example: The present change rate of the throttle opening is different from an average change rate of the throttle opening up to this point by more than a predetermined difference, or the present throttle operation frequency is different from an average throttle operation frequency up to this point by more than a predetermined frequency, or the present acceleration is different from an average acceleration up to this point by more than a predetermined acceleration amount.
  • the TCU 140 starts learning the present driving pattern represented by indices including throttle opening, throttle operation frequency and vehicle acceleration at step S 250 , and then controls the CVT according to the target speed ratio.
  • the driving pattern learning can be performed using a function that processes the driving pattern index in such a way that a function increases/decreases the throttle opening index according to whether the throttle opening change rate is greater than or less than the average throttle opening change rate, increases/decreases the throttle operation frequency index according to whether the throttle operation frequency is greater than or less than the average throttle operation frequency, and increases/decreases the vehicle's acceleration index according to whether the vehicle's acceleration is greater than or less than the vehicle's average acceleration.
  • the TCU 140 controls the CVT according to the previously calculated target speed ratio at step S 260 . If the learning condition is not satisfied at step S 240 , the TCU 140 controls the CVT 130 according to the target speed ratio calculated at step S 220 without learning the driving pattern.
  • the CVT control method of the present invention controls the CVT in a continuously variable speed ratio between the economy and power modes on the basis of the driving pattern index so as to reflect the driver's driving pattern well as well as in the economy mode so as to obtain the maximum mileage when the vehicle is running at a constant speed. This eliminates the inconvenience of manual mode selection.
  • the driving pattern index is accumulatively updated and learned to reflect the latest driving pattern so as to prevent discontinuous driving pattern index changes in spite of the driver's abrupt change of the driving pattern, resulting in stable speed ratio control.
US09/898,619 2000-11-06 2001-07-03 Method for controlling continuously variable transmission Expired - Fee Related US6480775B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
KR00-65483 2000-11-06
KR10-2000-0065483A KR100373027B1 (ko) 2000-11-06 2000-11-06 무단 변속기의 변속비 제어방법
KR2000-65483 2000-11-06

Publications (2)

Publication Number Publication Date
US20020082758A1 US20020082758A1 (en) 2002-06-27
US6480775B2 true US6480775B2 (en) 2002-11-12

Family

ID=19697337

Family Applications (1)

Application Number Title Priority Date Filing Date
US09/898,619 Expired - Fee Related US6480775B2 (en) 2000-11-06 2001-07-03 Method for controlling continuously variable transmission

Country Status (6)

Country Link
US (1) US6480775B2 (zh)
JP (1) JP2002156032A (zh)
KR (1) KR100373027B1 (zh)
CN (1) CN1222705C (zh)
AU (1) AU772072B2 (zh)
DE (1) DE10135959B4 (zh)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020142886A1 (en) * 2001-03-30 2002-10-03 Takayuki Kubo Speed shift control apparatus of automatic transmission
US20060065239A1 (en) * 2004-09-30 2006-03-30 Honda Motor Co., Ltd. Vehicular performance control system and method, and vehicle incorporating same
US20060185917A1 (en) * 2005-02-22 2006-08-24 Honda Motor Co., Ltd. Control mechanism and display for hybrid vehicle
US20090143191A1 (en) * 2007-11-30 2009-06-04 Milton Carter Hubbard Power train control system
US20110190968A1 (en) * 2010-02-03 2011-08-04 Toyota Motor Engineering & Manufacturing North America, Inc. Method and system for more efficient operation of plug-in electric vehicles
US20120016562A1 (en) * 2009-03-31 2012-01-19 Takashi Tetsuka Vehicle speed limiting system
US9200702B2 (en) 2014-05-01 2015-12-01 Ford Global Technologies, Llc Driver aware adaptive shifting

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005233371A (ja) * 2004-02-23 2005-09-02 Aisin Seiki Co Ltd 油圧特性値の設定方法
ES2286958B1 (es) * 2005-07-11 2008-09-01 Honda Motor Co., Ltd Sistema de control de vehiculo, sistema de control de transmision continuamente variable y metodo.
KR101518891B1 (ko) 2013-05-31 2015-05-12 현대자동차 주식회사 차량용 변속 제어 장치 및 방법
KR101459473B1 (ko) * 2013-08-30 2014-11-10 현대자동차 주식회사 차량용 자동 변속기의 변속 제어 방법
KR101484249B1 (ko) 2014-09-22 2015-01-16 현대자동차 주식회사 차량의 주행 모드 제어 장치 및 방법
KR20160034769A (ko) 2014-09-22 2016-03-30 현대자동차주식회사 자동변속기의 변속 제어 장치 및 방법
CN106438779B (zh) * 2016-09-22 2019-01-15 中国第一汽车股份有限公司 商用车无同步器变速器中间轴制动器自适应控制方法
CN115492929B (zh) * 2022-09-01 2023-10-27 中国第一汽车股份有限公司 变速器速比的控制方法、控制装置、存储介质、车辆

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4793217A (en) * 1985-09-17 1988-12-27 Toyota Jidosha Kabushiki Kaisha Method and apparatus for controlling power transmitting system for automotive vehicle, including continuously variable transmission and auxiliary transmission
US5114383A (en) * 1989-09-30 1992-05-19 Suzuki Jidosha Kogyo Kabushiki Kaisha Apparatus for controlling continuous variable transmission
US5247859A (en) * 1989-09-06 1993-09-28 Mazda Motor Corporation Shift control system for automatic transmission
US5685800A (en) * 1995-03-16 1997-11-11 Nissan Motor Co., Ltd. Control device for engine fuel supply
US5976054A (en) * 1997-06-27 1999-11-02 Nissan Motor Co., Ltd. Shift shock reducing apparatus of CVT equipped vehicle
US6138070A (en) * 1997-08-12 2000-10-24 Nissan Motor Co., Ltd. Controller for a continuously variable transmission
US6157885A (en) * 1998-01-09 2000-12-05 Honda Giken Kogyo Kabushiki Kaisha Vehicle motive force control system
US6174261B1 (en) * 1998-06-15 2001-01-16 Nissan Motor Co., Ltd. Speed controller and control methods of continuously variable transmission
US6244986B1 (en) * 1997-03-07 2001-06-12 Nissan Motor Co., Ltd. Shift control apparatus for continuously variable transmission

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4337957C2 (de) * 1992-11-12 2002-04-11 Volkswagen Ag Schalteinrichtung für ein Getriebe
DE19511863C2 (de) * 1995-03-31 1998-08-20 Daimler Benz Ag Automatgetriebesteuerung mit betriebsweisenadaptivem Schaltverhalten
DE19802075A1 (de) * 1998-01-21 1999-07-22 Volkswagen Ag Verfahren zur Übersetzungsregelung eines stufenlosen Automatikgetriebes (CVT-Getriebe) eines Kraftfahrzeugs
JP4178573B2 (ja) * 1998-01-30 2008-11-12 マツダ株式会社 自動変速機の制御装置

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4793217A (en) * 1985-09-17 1988-12-27 Toyota Jidosha Kabushiki Kaisha Method and apparatus for controlling power transmitting system for automotive vehicle, including continuously variable transmission and auxiliary transmission
US5247859A (en) * 1989-09-06 1993-09-28 Mazda Motor Corporation Shift control system for automatic transmission
US5114383A (en) * 1989-09-30 1992-05-19 Suzuki Jidosha Kogyo Kabushiki Kaisha Apparatus for controlling continuous variable transmission
US5685800A (en) * 1995-03-16 1997-11-11 Nissan Motor Co., Ltd. Control device for engine fuel supply
US6244986B1 (en) * 1997-03-07 2001-06-12 Nissan Motor Co., Ltd. Shift control apparatus for continuously variable transmission
US5976054A (en) * 1997-06-27 1999-11-02 Nissan Motor Co., Ltd. Shift shock reducing apparatus of CVT equipped vehicle
US6138070A (en) * 1997-08-12 2000-10-24 Nissan Motor Co., Ltd. Controller for a continuously variable transmission
US6157885A (en) * 1998-01-09 2000-12-05 Honda Giken Kogyo Kabushiki Kaisha Vehicle motive force control system
US6174261B1 (en) * 1998-06-15 2001-01-16 Nissan Motor Co., Ltd. Speed controller and control methods of continuously variable transmission

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020142886A1 (en) * 2001-03-30 2002-10-03 Takayuki Kubo Speed shift control apparatus of automatic transmission
US20060065239A1 (en) * 2004-09-30 2006-03-30 Honda Motor Co., Ltd. Vehicular performance control system and method, and vehicle incorporating same
US7475746B2 (en) * 2004-09-30 2009-01-13 Honda Motor Co., Ltd. Vehicular performance control system and method, and vehicle incorporating same
US20060185917A1 (en) * 2005-02-22 2006-08-24 Honda Motor Co., Ltd. Control mechanism and display for hybrid vehicle
US7617894B2 (en) * 2005-02-22 2009-11-17 Honda Motor Co., Ltd. Control mechanism and display for hybrid vehicle
US20090143191A1 (en) * 2007-11-30 2009-06-04 Milton Carter Hubbard Power train control system
US7955217B2 (en) 2007-11-30 2011-06-07 Caterpillar Inc. Power train control system
US20120016562A1 (en) * 2009-03-31 2012-01-19 Takashi Tetsuka Vehicle speed limiting system
US8296034B2 (en) * 2009-03-31 2012-10-23 Honda Motor Co., Ltd. Vehicle speed limiting system
US20110190968A1 (en) * 2010-02-03 2011-08-04 Toyota Motor Engineering & Manufacturing North America, Inc. Method and system for more efficient operation of plug-in electric vehicles
US8855840B2 (en) 2010-02-03 2014-10-07 Toyota Motor Engineering & Manufacturing North America, Inc. Method and system for more efficient operation of plug-in electric vehicles
US9200702B2 (en) 2014-05-01 2015-12-01 Ford Global Technologies, Llc Driver aware adaptive shifting

Also Published As

Publication number Publication date
JP2002156032A (ja) 2002-05-31
DE10135959B4 (de) 2005-03-31
AU772072B2 (en) 2004-04-08
DE10135959A1 (de) 2002-05-08
CN1353259A (zh) 2002-06-12
AU5596801A (en) 2002-05-09
KR100373027B1 (ko) 2003-02-25
US20020082758A1 (en) 2002-06-27
KR20020035258A (ko) 2002-05-11
CN1222705C (zh) 2005-10-12

Similar Documents

Publication Publication Date Title
US6480775B2 (en) Method for controlling continuously variable transmission
US5785627A (en) Torque feedback shift control device and method
US5688207A (en) Control apparatus for automatic transmission and control method therefore
US20040002803A1 (en) Shift control method and apparatus of an automatic transmission
JPH05240073A (ja) エンジン制御装置
EP0457585A2 (en) System for and method of controlling automatic transmission
US5695427A (en) Automatic transmission control system
EP1643163A2 (en) System and method of compensating heating performance of continuously-variable-transmission-equipped vehicle
JP2797502B2 (ja) 自動変速機の直結クラッチ制御装置
KR100419948B1 (ko) 적합형변속기
JPH07239021A (ja) 自動変速機の制御装置
JP3648273B2 (ja) 車両の自動切換式変速機の操作方法および操作装置
US6558294B1 (en) Method and apparatus for controlling an automatic gearbox
JP3460528B2 (ja) 車両の駆動力制御装置
EP1557590A1 (en) Automatic gear shift controller
JP3003757B2 (ja) 車両の駆動力制御装置
JP3418414B2 (ja) 内燃機関のトルク制御方法及びトルク制御装置
KR20230024493A (ko) 차량의 변속 제어 장치 및 그 방법
US5983153A (en) System for determining gear ratio changes for an automatic transmission
JP2005291174A (ja) 車両用エンジンのトルク制御装置
JPH0587220A (ja) 自動変速機の制御装置
JP2581303Y2 (ja) 自動変速機の変速時ライン圧学習制御装置
JP3090494B2 (ja) 自動変速機の制御方法および制御装置、並びに自動車
JPH10227237A (ja) エンジンのトルク制御装置
JPH03125062A (ja) 車両用無段変速機の変速制御装置

Legal Events

Date Code Title Description
AS Assignment

Owner name: HYUNDAI MOTOR COMPANY, KOREA, REPUBLIC OF

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CHO, YOON-HO;REEL/FRAME:011970/0940

Effective date: 20010625

FPAY Fee payment

Year of fee payment: 4

FEPP Fee payment procedure

Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20141112